.tab {
  width: 500px;
  margin: 0 auto; }
  .tab .tab_btn li {
    float: left;
    width: 100px;
    height: 40px;
    line-height: 40px;
    font-size: 18px;
    text-align: center;
    cursor: pointer; }
    .tab .tab_btn li.cur {
      background: cornflowerblue;
      color: #fff; }
  .tab .tab_list li {
    display: none;
    border: 1px solid cornflowerblue;
    height: 200px; }
    .tab .tab_list li.cur {
      display: block; }
